plot(c(-1, 1), c(-1, 1))
d = rotate.parabola(theta1 = 30, theta2 = 90, rou1 = 0.8)
lines(d); text(d[1, 1], d[1, 2], "start_30")
d = rotate.parabola(theta1 = 50, theta2 = 70, rou1 = 0.8)
lines(d); text(d[1, 1], d[1, 2], "start_50")
d = rotate.parabola(theta1 = 270, theta2 = 330, rou1 = 0.8, rou.ratio = 0.3)
lines(d); text(d[1, 1], d[1, 2], "start_270")
d = rotate.parabola(theta1 = 10, theta2 = 300, rou1 = 0.8, rou.ratio = 0.3, n = 5)
lines(d); text(d[1, 1], d[1, 2], "start_10")
d = rotate.parabola(theta1 = 240, theta2 = 360, rou1 = 0.8)
lines(d); text(d[1, 1], d[1, 2], "start_240")
d = rotate.parabola(theta1 = 290, theta2 = 40, rou1 = 0.8)
lines(d); text(d[1, 1], d[1, 2], "start_290")
d = rotate.parabola(theta1 = 180, theta2 = 150, rou1 = 0.8)
lines(d); text(d[1, 1], d[1, 2], "start_180")
